Pulsed interrogation signal in harmonic EAS system

摘要

An electronic article surveillance system includes generating circuitry for generating an interrogation signal. The generating circuitry includes an interrogation coil for radiating the interrogation signal in an interrogation zone. A marker is secured to an article appointed for passage through the interrogation zone, and includes an active element for generating a marker signal including harmonic signal components at harmonics of an operating frequency of the generating circuitry. Detecting circuitry detects the harmonic signal components of the marker signal generated by the active element. The generating circuitry generates the interrogation signal in the form of discrete pulses and the detecting circuitry is operated concurrently with the generating circuitry.